Scored piston 560

[Marsh Monkey]

my saw has been playing up for a couple of days and I was out cutting today and it just stopped dead after being really sulky. I took the exhaust off and noticed the piston was lightly scored, is this terminal or can it be honed and made good? 

[Stubby]

2 minutes ago, Marsh Monkey said:

my saw has been playing up for a couple of days and I was out cutting today and it just stopped dead after being really sulky. I took the exhaust off and noticed the piston was lightly scored, is this terminal or can it be honed and made good? 

Depends on how damaged it is . Usually the bore can be salvaged by removing the aluminum transfer and a new piston and ring . 

[Ratman]

Try to identify your initial cause, last thing you want to do is rebuild and relive at a cost again.

[Stubby]

39 minutes ago, Ratman said:

Try to identify your initial cause, last thing you want to do is rebuild and relive at a cost again.

This .

[Wedgebanger]

I'm wondering if you got an air leak somewhere..  other than that... oil in the fuel

 

so a p&v test first,  but my bet is a slight leak in the crank seal

[spudulike]

What oil are you using?

[Marsh Monkey]

mostly been using stihl red oil or oregon oil should i pay the extra and get the swank green stuff? i usually run at 45:1 as a couple of folk have said its better to run stuff a bit rich

 

[Marsh Monkey]

i think a lot of the cause has been the state of the last few jobs we've been on; wetland and i do mean wet, job spec is for super low stumps so it been wet peat cutting with bio oil a winning combo for any saw

[Marsh Monkey]

Here the state of a site last week

[spudulike]

All Strato engines should be run on either semi or full synthetic.....so....."the green stuff"!! Your hand book should have made that clear.

These machines sniff fuel using much less than their earlier models. Because of this, far less oil is seen on the bearings, bore and all moving parts.

Stihl Red is just not good enough for these modern machines and you aren't the only one!

If you are lucky, a new piston and a bit of work on the bore should see it come back. It would be interesting to see an AT download as it will tell you how the saw fuel was set at the time it failed.